I went on vacation to England for two weeks, and I went to the beach. (the beach was rocks.. not sand, how weird!) and I picked out a few rocks and brought them home with me. How should I go about to treating them, so that they can be placed inside my aquarium?

you can either boil them (careful they don't explode) or soak them in extremely hot tap water for a full week but change the water twice a day, don't use conditioner till the last day and use 4x the normal amount and they should be good